"We often see that when a storm weakens, people let down their guard completely. You shouldn't do that," he told Associated Press news agency.

The eye of the storm came ashore over the Yucatan Peninsula, about 170 miles (270km) south of Cancun, early on Tuesday in a sparsely populated area near the town of Majahual, where hundreds of homes were destroyed.

It lashed low-lying Mayan communities, and rain, poor communications and impassable roads made it hard to establish how they had fared in the storm.

President Felipe Calderon, who has cut short his visit to Canada for the Nafta summit, went to the affected areas. He said relief efforts would focus on these communities.

Ancient Mayan ruins were also in the hurricane's path, but officials from Mexico's National Anthropology and History Institute told AP that none of the archaeological sites in Quintana Roo and Yucatan were damaged.

Andrea Montalvo, of the US-based Spanish-language Telemundo television network, said the storm was wreaking havoc in the town of Chetumal, to the east of Majahual.

"Inside the hotel it is really bad, every 10 or 15 minutes you can hear windows shattering and people are coming out of their rooms in panic," she said.

"If this is how it is here in this hotel, which is pretty solid, I don't want to think about how it is there."

City officials said there were power cuts as the wind knocked over trees and sent debris flying through the air.

Further south, most of Belize was without power. Officials in Belize City closed hospitals and urged people to head inland, saying the town's shelters were not strong enough.

US President George W Bush offered aid to help hurricane victims, saying: "We stand ready to help".

"The American people care a lot about the human condition in our neighbourhood, and when we see human suffering we want to do what we can," he said.

Fleeing the storm

The hurricane has already claimed at least 12 lives in the eastern Caribbean.